Apparatus for gripping and holding diagnostic cassettes

ABSTRACT

The invention relates generally to an apparatus for acquiring, holding, and enabling the movement of a cassette-shaped article, such as a reagent or sample cassette, which may be part of an automated diagnostic analyzer, such that the apparatus can tolerate a significant degree of cassette misplacement and/or misalignment during the acquisition maneuver. The invention provides simultaneous two-dimensional movement of the acquiring gripper jaws such that the inter-jaw distance decreases at the same time as movement in an upward vertical direction is provided while the jaw movement is adequately smooth so as not to disturb the physical state of the sample.

FIELD OF THE INVENTION

The invention relates generally to an apparatus for gripping acassette-shaped article, particularly for acquiring, holding, andenabling the movement a reagent or sample cassette as part of anautomated diagnostic analyzer.

BACKGROUND OF THE INVENTION

Diagnostic clinical analyzers continue to become more sophisticatedespecially with respect to the handling and movement of patient samplesand associated reagents between multiple locations. A plethora ofincreasing complex pick and place transports have evolved into roboticsystems capable of two-dimensional, and in some cases, three-dimensionalmovement of patient sample containers. However, the evolution ofapparatuses to physically acquire and hold such containers has notadvanced especially when such containers are not simple test tubes, suchas, for example, foil sealed cassettes for agglutination reactions asshown in U.S. Pat. No. 5,780,248 incorporated herein by reference in itsentirety. Furthermore, such patient sample container acquisition reliesupon a small number of fundamental mechanisms. Cam driven machines offerthe smoothest motion and control of acceleration and deceleration. Theycan run at high cyclic rate, however, they are big, heavy and notsuitable for applications where space is limited. Hydraulic/pneumaticdriven machines are more compact and easier to use, but because theyusually use hydraulic/pneumatic pressure to drive the components againsthard stops, they create impact (which is particularly important inhandling cassettes containing whole blood components) and result innoisy machines of low cyclic rate. Servo motor/stepper motor drivenmachines are usually slower, can be higher in cost, but have moreflexible operation. U.S. Pat. No. 5,681,530 relates to a transportsystem for fluid analysis instruments that includes a cassette gripperand conveyor, incorporated herein by reference in its entirety.

With respect to acquisition of the patient sample container, existingmechanisms tend to be specific to test tubes and are mechanicallycomplex with many parts. In addition to having very limited capabilityto acquire and hold misplaced patient sample containers because of alimited motion function, these units are expensive to manufacture andoften have reduced reliability. Furthermore, most mechanisms impartsignificant inertial forces to the patient sample container which isvery undesirable and potentially can result in altering the sample'sphysical properties. A number of these systems are noted as follows:U.S. Pat. No. 4,002,247 entitled “Machine for picking up, transferring,turning and placing parts,” U.S. Pat. No. 4,411,576 entitled “Pick andplace mechanism,” U.S. Pat. No. 4,975,018 entitled “Linear unit fortransferring objects,” U.S. Pat. No. 5,249,663 entitled “Apparatus toload workpieces,” U.S. Pat. No. 5,333,720 entitled “Apparatus tomanipulate workpieces,” U.S. Pat. No. 5,467,864 entitled “Dual purposeapparatus to manipulate workpieces,” U.S. Pat. No. 5,564,888 entitled“Pick and place machine,” U.S. Pat. No. 6,264,419 entitled “Robot arm,”U.S. Pat. No. 6,293,750 entitled “Robotics for transporting containersand objects within an automated analytical instrument and service toolfor servicing robotics,” U.S. Pat. No. 6,374,982 entitled “Robotics fortransporting containers and objects within an automated analyticalinstrument and service tool for servicing robotics,” U.S. Pat. No.6,843,357 entitled “Two-axis robot for specimen transfer,” U.S. Pat. No.6,889,119 entitled “Robotic device for loading laboratory instruments,”U.S. Pat. No. 7,131,361 entitled “Workpiece-transfer device,” U.S. Pat.No. 7,448,294 entitled “Robotic devices,” U.S. Pat. No. 7,563,067entitled “Robot,” PCT Publication No. WO2008067847 entitled “Containertransfer apparatus with automatic positioning compensation,” and U.S.Publication No. 2010/0150688 entitled “Workpiece transfer system.”

None of the prior references noted above disclose an apparatus capableof operating in a confined space, having a minimal number of parts,having the ability to acquire patient samples in cassettes withsignificant misalignment, and imparting a movement of the apparatusparticularity conducive to the acquisition and holding of non-testtube-shaped patient sample containers.

SUMMARY OF THE INVENTION

An object of the invention is to solve or at least improve upon thedeficiencies of prior art noted above.

One aspect of the present invention is directed to an apparatus forgripping a cassette-shaped article. The apparatus includes: a supporthousing; a linear actuator movable along an x-axis relative to thesupport; a set of jaws for gripping the cassette-shaped article, eachjaw having a proximal end and a distal end, the distal end being adaptedfor gripping the cassette-shaped article; a movable node located at theproximal end of each jaw for connecting each jaw to the linear actuator;a fixed node relative to the support located between the proximal anddistal end of each jaw for connecting each of the jaws to the support,wherein the fixed node is indirectly located on the jaws and isconnected to the jaws via linkage and a movable node on the jaws; andwherein movement of the linear actuator provides motion to the movablenode in an x- and y-axis thereby rotating the jaws around the fixed noderesulting in the jaws opening and closing.

Another aspect of the present invention is directed to an apparatus forgripping a cassette-shaped article. The apparatus includes: a supporthousing; a linear actuator movable along an x-axis relative to thesupport; a set of jaws for gripping the cassette-shaped article, eachjaw having a proximal end and a distal end, the distal end being adaptedfor gripping the cassette-shaped article; a movable node located at theproximal end of each jaw for connecting each jaw to the linear actuator;a fixed node relative to the support located between the proximal anddistal end of each jaw for connecting each of the jaws to the support,wherein the fixed node is directly located on the jaws; a drive linkageconnected to the linear actuator at the center thereof, the drivelinkage having elongated slots on either side of the center, the movablenodes being slidably engaged in the slots, whereupon movement of thelinear actuator moves the drive linkage which imparts linear motion tothe movable node in a direction perpendicular to the motion of the slidethereby rotating the jaws around the fixed node resulting in the jawsopening and closing; a set of registration dowels attached to the bottomof the housing near the distal end of each of the jaws which arepositioned to be capable of being abutted by the cassette-shaped articleonce the cassette-shaped article has been acquired, a compliance blockis located at the upper end of the housing; and a spring is placed underthe compliance block, enabling the housing to slightly tilt, whereinacquisition of the cassette is guided by the registration dowels and themovement of the cassette-shaped article is guided by the complianceblock and spring allowing for possible misalignment of the apparatusrelative to the cassette-shaped article.

Still, another aspect of the invention is directed to a method forgripping a cassette-shaped article. The method includes: providing asupport housing; providing a linear actuator movable along an x-axisrelative to the support; providing a set of jaws for gripping thecassette-shaped article, each jaw having a proximal end and a distalend, the distal end being adapted for gripping the cassette-shapedarticle; providing a movable node located at the proximal end of eachjaw for connecting each jaw to the linear actuator; providing a fixednode relative to the support located between the proximal and distal endof each jaw for connecting each of the jaws to the support, wherein thefixed node is indirectly located on the jaws and is connected to thejaws via linkage and a movable node on the jaws; positioning the housingto be located above the cassette-shaped article to be gripped; movingthe linear actuator which provides motion to the movable node in an x-and y-axis thereby rotating the jaws around the fixed node resulting inthe jaws closing and acquiring the cassette-shaped article.

Yet another aspect of the invention is directed to a method for grippinga cassette-shaped article. The method includes: providing a supporthousing; providing a linear actuator movable along an x-axis relative tothe support; providing a set of jaws for gripping the cassette-shapedarticle, each jaw having a proximal end and a distal end, the distal endbeing adapted for gripping the cassette-shaped article; providing amovable node located at the proximal end of each jaw for connecting eachjaw to the linear actuator; providing a fixed node relative to thesupport located between the proximal and distal end of each jaw forconnecting each of the jaws to the support, wherein the fixed node isdirectly located on the jaws; providing a drive linkage connected to thelinear actuator at the center thereof, the drive linkage havingelongated slots on either side of the center, the movable nodes beingslidably engaged in the slots; providing a set of registration dowelsattached to the bottom of the housing near the distal end of each of thejaws which are positioned to be capable of being abutted by thecassette-shaped article once the cassette-shaped article has beenacquired; providing a compliance block at the upper end of the housing,and a spring under the compliance block, enabling the housing todeflect; positioning the housing to be located above the cassette-shapedarticle to be gripped; moving the linear actuator which moves the drivelinkage which imparts linear motion to the movable node in a directionperpendicular to the motion of the slide thereby rotating the jawsaround the fixed node resulting in the jaws closing and acquiring thecassette-shaped article; wherein acquisition of the cassette is guidedby the registration dowels and the movement of the cassette-shapedarticle is guided by the compliance block and spring allowing forpossible misalignment of the apparatus relative to the cassette-shapedarticle.

In a preferred embodiment of the invention the apparatus has the abilityto accurately acquire and securely hold diagnostic cassettes even in thepresence of moderate misalignments.

Still, another preferred embodiment of the invention providesimultaneous two-dimensional movement of the acquiring jaws of thegripping apparatus such that the inter-jaw distance decreases at thesame time while providing movement in an upward vertical direction thususing a minimum of space.

Yet, another preferred embodiment of the invention provides an apparatushaving a minimal number of parts and is therefore inexpensive tomanufacture while having high reliability.

In another preferred embodiment, the apparatus is constructed of acombination of gears, racks, and mechanical linkage which provides asmooth movement superior to cams, pneumatic, or hydraulic driven devicesand is particularity adept at not disturbing the physicalcharacteristics of sensitive patient samples.

In a preferred embodiment, the invention incorporates a spring-loadedvertical drive movement such that the apparatus can tolerate asignificant degree of cassette misplacement and/or gripper misalignmentduring the cassette acquisition maneuver. The movement of the mechanicalparts acquiring the cassette is such that physical state of the sampleis not disturbed and that the mechanical act of cassette acquisitiontakes place in a minimum of space.

In another preferred embodiment, the invention incorporates a Hoekenlinkage.

In yet another preferred embodiment, the invention registers the patientsample container against a set of registration dowels enabling opticalsensor or other feedback indicating that the patient sample containerhas been positively acquired. Further objects, features, and advantagesof the present application will be apparent to those skilled in the artfrom detailed consideration of the embodiments that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of the gripping and holding apparatusin the open position according to Configuration 1 of a preferredembodiment of the present invention. The apparatus, also known as thecassette gripper unit, is contained within a housing 102 which holds alinear actuator, for example, an electric servo motor 104 coupled to orconfigured as a leadscrew 105. The servo motor 104 has a shaftconfigured as a lead screw 105 which is threaded into a rack nut 103 or,alternatively coupled to the leadscrew with a rotating coupling. Asector gear linkage 106 is rotatably attached to the housing 102 and isconfigured as a Hoeken linkage 107 containing a set of jaws 109. The endof the set of jaws 109 attached to the sector gear linkage 106 isdesignated as the proximal end and the end of the set of jaws 109 thatgrips the diagnostic cassette 110 is designated as the distal end. Theupward movement of a cassette 110 is constrained by a set ofregistration dowels 108. A compliance block 100, such as an elastomericblock, and spring 101 allow the cassette gripper unit to acquire andplace cassettes with a degree of misalignment. The presence or absenceof a cassette 110 securely pressed against the registration dowels 108is sensed by an optical sensor 111.

FIG. 2 is a schematic front view of the gripping and holding apparatus,also known as the cassette gripper unit, in the closed positionaccording to Configuration 1 of a preferred embodiment of the presentinvention. The apparatus is contained within a housing 102 which holds alinear actuator, for example, an electric servo motor 104 coupled to orconfigured as a leadscrew 105. The servo motor 104 has a shaftconfigured as a lead screw 105 which is threaded into a rack nut 103 or,alternatively coupled to the leadscrew with a rotating coupling. Asector gear linkage 106 is rotatably attached to the housing 102 and isconfigured as a Hoeken linkage 107 containing a set of jaws 109. Theupward movement of a cassette 110 is constrained by a set ofregistration dowels 108. A compliance block 100 and spring 101 allow thecassette gripper unit to acquire and place objects with a degree ofmisalignment. The presence or absence of a cassette 110 securely pressedagainst the registration dowels 108 is sensed by an optical sensor 111.

FIG. 3 is a schematic front view of the gripping and holding apparatus,also known as the cassette gripper unit, in the open position accordingto Configuration 2 of a preferred embodiment of the present invention.The apparatus is contained in a housing 102 which holds a linearactuator, for example, an electric servo motor 104 coupled to orconfigured as a leadscrew. The servo motor 104 has a shaft 301configured as a lead screw which is threaded into a drive link 300 or,alternatively coupled to the leadscrew with a rotating coupling. A setof jaws 302 is provided where the upper end of the set of jaws 302 whichis attached to the drive link 300 is designated as the proximal end andthe lower end of the set of jaws 302 which grips the diagnostic cassetteis designated as the distal end. The set of jaws 302 is attached to thedrive link 300 such that the proximal end of the jaws 302 is allowed toslide horizontally within the drive link 300. The upward movement of acassette 110 is constrained by a set of registration dowels 108. Acompliance block 100 and spring 101 allow the cassette gripper unit toacquire and place objects with a degree of misalignment. The presence orabsence of a cassette 110 securely pressed against the registrationdowels 108 is sensed by an optical sensor 111.

FIG. 4 is a schematic front view of the gripping and holding apparatusin the closed position apparatus, also known as the cassette gripperunit, according to Configuration 2 of a preferred embodiment of thepresent invention. The apparatus is contained in a housing 102 whichholds a linear actuator, for example, an electric servo motor 104coupled to or configured as a leadscrew. The servo motor 104 has a shaft301 configured as a lead screw which is threaded into a drive link 300or, alternatively coupled to the leadscrew with a rotating coupling. Aset of jaws 302 is attached to the drive link 300 such that the proximalend of the jaws 302 is allowed to slide horizontally within the drivelink 300. The upward movement of a cassette 110 is constrained by a setof registration dowels 108. A compliance block 100 and spring 101 allowthe cassette gripper unit to acquire and place objects with a degree ofmisalignment. The presence or absence of a cassette 110 securely pressedagainst the registration dowels 108 is sensed by an optical sensor 111.

FIG. 5 is a schematic diagram of the details of the Configuration 1linkage. A motor shaft configured as a lead screw 105 is threaded into arack nut 103. The sector gear linkage 500 rotating about a joint denotedby node A1 is engaged into the rack nut 103 such that a set of jaws 501moves in response to the rotation of the lead screw 105 via primaryjoints at nodes B1 and B2, and a secondary joint at node A2 associatedwith a link arm 502. The movement of the distal end of the set of jaws501 is indicated by arrows 503. Joints denoted by nodes A1 and A2 arelink-to-housing rotationally pinned and joints denoted by nodes B1 andB2 are link-to-link pinned.

FIG. 6 is a schematic diagram of the details of the Configuration 2linkage. A motor shaft configured as a lead screw 301 is threaded into adrive crossbar slider 300. The upper end of a set of jaws 302 is engagedinto the drive crossbar slider 300 such that the proximal end of the setof jaws 302 slides horizontally left or right within the drive crossbarslider 300 in response to the rotation of the lead screw 301. Themovement of the distal end of the set of jaws 302 is circular and isindicated by arrows 600. Joints denoted by node D are link-to-housingrotationally pinned and joints denoted by node C are link-to-crossbarslider pinned (such that horizontal left or right movement is allowed).

FIG. 7 is a diagram of the Hoeken Linkage coupler curve. The movement ofthe distal end of the link arm 701 is indicated by a dotted curve 700.The proximal end of the link arm 701 is connected to the sector gearlink 703 at the joint denoted by node B1. The sector gear link 703 isrotationally attached to the housing 102 at the joint denoted by nodeA1. A connecting link 702 is attached to the link arm 701 at the jointdenoted by node B2 and is rotationally attached to the housing at thejoint denoted by node A2 is the third component of the Hoeken linkage.Rotation of the sector gear link 703 imparts movement to the distal endof the link arm 701. Joints denoted by nodes A1 and A2 arelink-to-housing rotationally pinned and joints denoted by nodes B1 andB2 are link-to-link pinned.

FIG. 8 is a schematic diagram of the details of the left element of theset of jaws 109 as shown in FIGS. 5 and 6. A profile of this element isshown in the front view, and in the side view of this element, atapering notch 800 is shown in the distal portion of the set of jaws109.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the present invention is described with respect to the preferredembodiments described below and shown in the figures, the presentinvention is limited only by the metes and bounds of the claims thatfollow.

The apparatus and methods described herein enable the rapid and secureacquisition of diagnostic cassettes in a diagnostic clinical analyzerfor subsequent movement within or removal from the analyzer. Examples ofknown diagnostic analyzers include immunodiagnostic analyzers such asthe Vitros® ECi immunodiagnostic analyzer or the Vitros® 3600immunodiagnostic analyzer, or clinical chemistry analyzers such as theVitros® 5,1 FS, or Vitros® 5600 all sold by Ortho-Clinical Diagnostics,Inc. Representative systems are disclosed, for example, in U.S.Published Patent Application No. 2003/0026733 and in U.S. applicationSer. No. 11/091,283 filed Mar. 28, 2005, both of which are incorporatedherein by reference in their entireties. Other examples include bloodimmunohematology analyzers used in blood typing operations, such asthose disclosed in U.S. Pat. Nos. 5,681,530 and 5,594,808, and blooddonor screening apparatus, such as those sold under the Ortho SummitSystem™ sold by Ortho-Clinical Diagnostics, Inc. As used herein, allsuch analyzers are collectively called “diagnostic analyzers.”

The benefits of the apparatus may include the ability to acquire thediagnostic cassette in the presence of minor misplacement ormisalignment of the cassette's position, the ability to acquire thecassette while transmitting a minimal amount of force to the patientsample, the ability to acquire the cassette in a minimal amount ofspace, the ability of the acquiring mechanism to have a minimal numberof parts with subsequent high reliability, and the ability to registeracquisition of the cassette and to signal that acquisition via optionalfeedback sensors.

For a general understanding of the disclosed technology, reference ismade to the drawings. In the drawings, like reference numerals have beenused to designate identical elements. In describing the disclosedtechnology, the following term(s) have been used in the description.

The term “housing” refers herein to a supporting structure, frame, cage,enclosure, encompassment, or substrate to which various other structuralelements are attached providing a measure of rigidity such that thecassette gripper apparatus can be used and moved as a unit.

The term “link” refers herein to a rigid body which contains at leasttwo nodes which are points for attachment to other links or a support. A“binary link” has two nodes; a “ternary link” has three nodes, etc.

A “node” refers herein to positions on a link where other links may beattached resulting in a joint.

A “joint” refers herein to a connection between two or more links (attheir nodes), which allows some motion, or potential motion, between theconnected links. Joints may be of the form of a “rotating pin joint”which allows one degree of freedom for movement or of the form of a“translating slider joint” which also allows one degree of freedom ofmovement, among others (see Robert L. Norton, Design of Machinery,3^(rd) edition, McGraw-Hill Book Company, 2003, which is herebyincorporated by reference).

The term “lead screw” refers herein to a mechanism designed to translaterotational motion into linear motion. This is accomplished by therotation of a threaded rod that has been inserted into a nut such thatwhen the threaded rod is rotated the nut is moved a specified lineardistance (depending upon the pitch of the threads in the rod).

The term “rack nut” refers herein to a lead screw nut having femalethreads, threaded into a lead screw, and held in a fixed orientationsuch that rotation of the lead screw produces linear motion in the racknut. Furthermore, at least one side of the rack nut has a rack structurewhich engages a circular pinion or gear such that linear motion of therack nut causes rotational motion of the pinion or gear.

One aspect of the invention is directed to an apparatus for gripping acassette-shaped article, such as a gripping apparatus for acquiring andholding a diagnostic cassette 110 while operating in a highly confinedspace. FIGS. 1 and 2 show Configuration 1 of the cassette gripper unit.This unit may be attached to a system, such as a diagnostic analyzer, byan arm (not shown) connected to the compliance block 100. Raising andlowering of the arm provides z-axis movement to the cassette gripperunit. The arm also provides movement in the x-axis and y-axis directionsto appropriately place the cassette 110. Other suitable mechanisms tosecure the unit to the analyzer and provide movement to the unit mayalso be used. The cassette gripper unit when being lowered may not beperfectly square with the top of the cassette being acquired and thecompliance block 100 in cooperation with the spring 101 allows thecassette gripper unit to tilt at a slight incline or gimbal slightlysuch that the top of the cassette is in light contact with bothregistration dowels 108. Hence, the mechanism has the ability toaccommodate a degree of misalignment between the cassette 110 and thebottom of the cassette gripper unit. The cassette gripper unit asdenoted by Configuration 1 includes a set of jaws 109 that while closingboth reduce the inter-jaw gap and at the same time provide verticalmovement. The exact movement profile is governed by the mechanicalconfiguration of a Hoeken's linkage 107, described more fully below inconnection with FIG. 7. A set of jaws 109 that operates in theaforementioned manner initially move downward and inward toward thecassette 110 being acquired subsequently providing lift in the verticaldirection 503. Ultimately the vertical movement causes the top of thediagnostic cassette 110 to be pushed securely against the registrationdowels 108. These registration dowels 108 may be composed of compliantmaterials such as rubber or soft, flexible polymer which deforms uponcontact with the diagnostic cassette 110. The deformation of theregistration dowels 108 provides a tension between the diagnosticcassette 110 and the jaw 109 insuring a firm and secure grip on thecassette 110. Also, the tapered notch 800 cut into the arm of the set ofjaws 109 tends to center the cassette in the set of jaws 109 allowingfor an additional degree of misalignment. The presence of the cassette110 in the proper position is sensed by an optical sensor 111 such thatan acquisition signal is sent terminating the application ofelectromotive force. Alternatively, the deformation of the registrationdowels may cause pressure to be applied to a micro-switch or straingauge-like sensor enabling the sending of a signal that the diagnosticcassette 110 has been acquired and is held in the proper position. Notethat the use of a Hoeken linkage 107 enables movement of the set of jaws109 using a very small amount of space, but at the cost of somemechanical complexity.

FIG. 1 is a schematic front view of a preferred embodiment of thegripping apparatus, also known as the cassette gripper unit, denoted asConfiguration 1. The various components of Configuration 1 are locatedwithin a housing 102 featuring a compliance block 100 and a spring 101to allow for slight positional misalignments between the registrationdowels 108 and the top edge of the cassette 110 as the cassette gripperunit is lowered. A servo motor 104 having a shaft configured as a leadscrew 105 is attached to the upper portion of the housing 102.Alternatively, the shaft of the servo motor 104 may be connected to aseparate lead screw by several commonly known mechanisms including arotating coupling. The lead screw 105 is threaded into a rack nut 103having racks on both the left and right sides. Sector gear links 106 areengaged into the rack nut 103 in a rack-and-pinion configuration andcomprise an essential component of the Hoeken linkage 107. In operation,the application of electromotive force to the servo motor 104 imparts aforward rotation of the shaft subsequently turning the lead screw 105causing the rack nut 103 to move linearly in a downward direction. Thisdownward movement of the rack nut 103 causes the sector gear links 106to rotate in a counter-clockwise manner, imparting movement to theHoeken linkage 107 resulting in simultaneous downward and inwardmovement followed by an upward motion 503 of the distal end of the setof jaws 109. The distal end of the set of jaws 109 contact thediagnostic cassette 110, center the cassette into the tapered notch 800,and move it slightly upwards such that the top of the cassette is forcedagainst the registration dowels 108. The presence of the cassette 110 inthe proper position is sensed by the optical sensor 111 such that anacquisition signal is sent terminating the application of electromotiveforce. Alternatively, the compression of the registration dowels causesa micro-switch or strain gauge-like sensor to trip, or alternatively, aload exceeding a specific threshold on the servo motor is reached, and,in either case, an acquisition signal is sent terminating theapplication of electromotive force. At this point the cassette 110 hasbeen acquired and is securely held for further movement by thediagnostic clinical analyzer.

FIG. 2 shows Configuration 1 in the closed position with the diagnosticcassette 110 in the fully acquired and held position.

Another aspect of the invention is directed to a gripping apparatushaving a minimal number of parts and, therefore, being less expensive tomanufacture, having high reliability, and having precise movements.Referring to FIGS. 3 and 4, the cassette gripper unit denoted byConfiguration 2 includes a set of jaws 302 that while closing bothreduce the distal inter-jaw gap and at the same time providing verticalmovement. However, unlike the Hoeken linkage of Configuration 1, eachside of the set of jaws 302 is rotationally pinned to the housing 102 ata single point near their mid-section. This only provides for the distalend of the set of jaws 302 to be able to close inwardly in a circularmotion. The distal end of a set of jaws 302 that operates in theaforementioned manner move inward toward the cassette 110 beingacquired, centers the cassette 110 in the tapered notch 800, andprovides lift in the vertical direction. The limited number of partscomprising the linkage (three) results in a mechanism having greaterprecision than Configuration 1 in that mistakes in manufacturing andmounting are multiplied by the number of members of the mechanism (seeRobert L. Norton, Design of Machinery, 3^(rd) edition, McGraw-Hill BookCompany, 2003, which is hereby incorporated by reference). Ultimatelythe vertical movement causes the top of the diagnostic cassette 110 tobe forced securely against the registration dowels 108. In a mannersimilar to Configuration 1, the presence of the cassette 110 in theproper position is sensed by the optical sensor 111 such that anacquisition signal is sent terminating the application of electromotiveforce. Alternatively, the compression of the registration dowels causesa micro-switch or strain gauge-like sensor to trip, or alternatively, aload exceeding a specific threshold on the servo motor is reached, suchthat an acquisition signal is sent terminating the application ofelectromotive force. At this point the cassette 110 has been acquiredand is securely held for further movement by the diagnostic clinicalanalyzer.

FIG. 3 is a schematic front view of a preferred embodiment of thegripping apparatus, known as the cassette gripper unit, denotedConfiguration 2. The various components of Configuration 2 are locatedwithin a housing 102 featuring a compliance block 100 and a spring 101to allow for positional misalignments between the gripper apparatus andthe position of the cassette during the initial downward movement toacquire the cassette in a manner similar to that of Configuration 1. Aservo motor 104 having a shaft configured as a lead screw 301 isattached to the upper portion of the housing 102. Alternatively, theshaft of the servo motor 104 could be attached to a lead screw by anumber of commonly known mechanisms including a rotating coupling. Thelead screw 301 is threaded into a drive link 300 to which the proximalportion of the set of jaws 302 have been pinned in a configuration knownas a translating slider joint such that sliding movement in thehorizontal direction is enabled. The set of jaws 302 have beenrotationally pinned to the housing 102 at about mid-length and are onlycapable of circular movement. In operation, the application ofelectromotive force to the servo motor 104 imparts a forward rotation ofthe shaft and subsequently turns the lead screw 301 causing the drivelink 300 to move linearly in an upward direction. This causes theproximal ends of the set of jaws 302 to move outward via the translatingslider joints. The distal end of the set of jaws 302 then move inwardlyin a circular motion. The distal ends of the set of jaws 302 contact thediagnostic cassette 110 and move it slight upwards such that the top ofthe cassette is forced against the registration dowels 108. In a mannersimilar to Configuration 1, the presence of the cassette 110 in theproper position is sensed by the optical sensor 111 such that anacquisition signal is sent terminating the application of electromotiveforce. Alternatively, the compression of the registration dowels causesa micro-switch or strain gauge-like sensor or, alternatively, athreshold exceeding load on the servo motor, such that an acquisitionsignal is sent terminating the application of electromotive force. Atthis point the cassette 110 has been acquired and is securely held forfurther movement within the diagnostic clinical analyzer. Note that theuse of a drive link 300 coupled with a set of jaws 302 capable of onlycircular movement requires greater space in which to operate relative toConfiguration 1, but results in a simpler mechanism having less cost andgreater reliability.

FIG. 4 shows Configuration 2 in the closed position with the diagnosticcassette 110 in the fully acquired and held position.

FIG. 5 shows further details of Configuration 1. Here the shaftconfigured as a lead screw 105 is shown threaded into the rack nut 103with the sector gear link 500 which is rotationally connected to a jointformed by node A1 and the housing 102, engaged into the rack (not shown)of the rack nut 103. As previously noted, the shaft of the servo motor104 could be simply connected to a lead screw. In particular, thecomponents of the Hoeken linkage 107 are detailed as (1) a sector gearlink 500 rotationally connected to a joint formed by node A1 and thehousing 102, (2) an arm link (or one-half of the set of jaws) 501 havingtwo joints the first joint formed by node B1 which connects the sectorgear link 500 and the arm link 501 and the second joint formed by nodeB2 which connects the connecting link 502 and the arm link 501, and (3)a connecting link 502 which has two joints the first joint formed bynode B2 connecting the arm link 501 and the connecting link 502 and thesecond joint formed by node A2 which rotationally connects theconnecting link 502 to the housing 102. It is important to note that thejoints of the Hoeken linkage 107 components are of two types (1) thetype designated as A1 or A2 has the link rotationally pinned to thehousing 102 and (2) the type designated as B1 or B2 has one linkrotationally pinned to another link. Hence, the sector gear link 500 andthe connecting link 502 being rotationally pinned to the housing 102 canonly rotate in a circular manner about the point at which they areconnected. Whereas, the arm link 501 is free to move such that thedistal end of the arm link 501 (or alternatively, the distal end of onecomponent of the set of jaws 501) traces the Hoeken movement 503.

FIG. 6 shows further details of Configuration 2. Here the servo motorshaft configured as a lead screw 301 is threaded into the drive link300. As previously noted, the shaft of the servo motor 104 could besimply connected to a lead screw. In particular, note that thismechanism is composed of only three mechanical parts. The proximal endof the arm link 302 (or one-half of the set of jaws) is connected to thedrive link 300 by a translating slider joint formed by node C and thearm link 302 is rotationally connected to the housing 102 by a jointformed by node D. Furthermore, it is important to note that the abovejoints are of two types (1) the type designated as D has the linkrotationally pinned to the housing 102 and (2) the type designated as Chas one link pinned to another link such that the connection is free toslide in one-dimension. Hence, the arm link 302 can only rotate aboutthe joint formed by node D in response to upward or downward movement ofthe drive link 300 where the translating slider joint formed by node Cto the arm link 302 is allowed to slide one-dimensionally in thehorizontal direction.

FIG. 7 shows a schematic diagram of the Hoeken's Linkage Coupler Curve.The Hoeken curve 700 is traced by distal end of the arm link 701 (oralternatively for the present invention, the distal end of one of thecomponents of the jaws) through rotation of the sector gear link 703 ascoupled to the arm link 701 and the connecting link 702. Connectionsbetween the links are of two types; a type A1 or A2 connection is wherethe link component is rotationally pinned to the housing 102 and a typeB1 or B2 connection is where one link is connected to another link. Notethat in the present invention that only the left most portion of theHoeken curve is utilized.

FIG. 8 shows details of the one component of the set of jaws 109. Notethat in the side view that there is a notch 800 cut into the distal endof the jaw. This notch 800 gently tapers such that upon closing of theset of jaws 109, the notch 800, which is larger than the thickness ofthe wall of the cassette 110, has a tendency to center the position ofthe cassette while it is being held.

In a particularly preferred embodiment, the apparatus according to thepresent invention is particularly suited for systems that detect andquantify agglutinates formed in response to immunological agglutinationreactions, i.e., immunohematology blood analyzers. In such systems, gelor glass bead micro particles are contained within a small column,referred to as a microcolumn. A reagent such as anti-IgG is dispensed ina diluent in the microcolumn and a test red blood sample is placed in areaction chamber above the column. The column, which is typically one ofa multitude of columns formed in a transparent cassette, is thencentrifuged. The cassette is handled by the cassette gripper accordingto the present invention. Such systems are described in U.S. Pat. Nos.5,681,530, 5,905,808 and 5,911,000, all of which are incorporated hereinby reference in their entirety. A typical cassette used in columnagglutination technology (CAT) is described in U.S. Pat. No. 5,780,248,described above.

In such systems, a cassette 110 stored in a storage unit is moved into adispensing condition below an opening in the unit. The cassette gripperunit, which is attached to a movable arm, moves in the direction thestorage unit until superimposed over the cassette 110 which is to beremoved from the storage unit. Thereafter, gripper unit contacts thecassette as described above, which is then clampingly engaged by gripperunit jaws 109. Thereafter, the cassette 110 is lifted outwardly of thestorage unit and may be passed by an adjacent bar code reader which willascertain information as to the proper orientation of the cassette, thatthe desired cassette has been removed from the storage unit, that thecassette has not reached its expiration dating, and miscellaneousinformation as to the sequence number and lot number of the cassette,all of which information may then be transmitted to the memory of acomputer and stored therein.

The cassette gripper unit then transports the cassette 110 to anincubator. At this point, a piercer punches one or more aperturesthrough the foil covering on the cassette. Blood and reagents may thenbe dispensed into the cassette 110, which may then be incubated.

The gripper unit then transports the cassette to a centrifuge, whichspins; for instance, initially for two minutes at 55 g and for threeminutes at 199 g, so as to provide for suitable admixing of the bloodsample and reagent in each of the respective wells. Upon completion ofthe centrifuging action, the gripper member engages the centrifugedcassette and transfers it to a read station. Upon completion of theread, the cassette is disposed of.

The foregoing is adapted to be computer program-controlled by a computerwhich is well known to those skilled in the art.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the methods and processes ofthis invention. Thus, it is intended that the present invention coversuch modifications and variations, provided they come within the scopeof the appended claims and their equivalents.

The disclosure of all publications cited above is expressly incorporatedherein by reference in their entireties to the same extent as if eachwere incorporated by reference individually.

We claim:
 1. An apparatus for gripping a cassette-shaped articlecomprising; a support housing; a linear actuator movable along an x-axisrelative to the support; a set of jaws for gripping the cassette-shapedarticle, each jaw having a proximal end and a distal end, the distal endbeing adapted for gripping the cassette-shaped article; a movable nodelocated at the proximal end of each jaw for connecting each jaw to thelinear actuator; a fixed node relative to the support located betweenthe proximal and distal end of each jaw for connecting each of the jawsto the support, wherein the fixed node is indirectly located on the jawsand is connected to the jaws via linkage and a movable node on the jaws;and wherein movement of the linear actuator provides motion to themovable node in an x- and y-axis thereby rotating the jaws around thefixed node resulting in the jaws opening and closing.
 2. An apparatusaccording to claim 1, further comprising: a sector gear linkage having atoothed side and a linkage extending away from the toothed side, the endof the linkage opposite the sector gear linkage connected to the movablenode; and a rack on the linear actuator, wherein the sector gear linkageteeth and the rack teeth are engaged and where movement of the rackrotates the sector gear linkage imparting motion to the linkage whichimparts motion to the jaws through the movable node.
 3. An apparatusaccording to claim 1, wherein the linear actuator comprises a motor anda rotatable lead screw driven by said motor.
 4. An apparatus accordingto claim 1, further comprising a set of registration dowels, acompliance block, and a spring, wherein acquisition of the cassette isguided by the registration dowels and the movement of thecassette-shaped article is guided by the compliance block and springallowing for possible misalignment of the apparatus relative to thecassette-shaped article.
 5. An apparatus according to claim 4, furtherwherein the set of registration dowels are attached to the bottom of thehousing near the distal end of each of the jaws and which are positionedto be capable of being abutted by the cassette-shaped article once thecassette-shaped article has been acquired, wherein the compliance blockis located at the upper end of the housing and the spring is placedunder the compliance block, enabling the housing to deflect.
 6. Anapparatus for gripping a cassette-shaped article comprising; a supporthousing; a linear actuator movable along an x-axis relative to thesupport; a set of jaws for gripping the cassette-shaped article, eachjaw having a proximal end and a distal end, the distal end being adaptedfor gripping the cassette-shaped article; a movable node located at theproximal end of each jaw for connecting each jaw to the linear actuator;a fixed node relative to the support located between the proximal anddistal end of each jaw for connecting each of the jaws to the support,wherein the fixed node is directly located on the jaws; a drive linkageconnected to the linear actuator at the center thereof, the drivelinkage having elongated slots on either side of the center, the movablenodes being slidably engaged in the slots, whereupon movement of thelinear actuator moves the drive linkage which imparts linear motion tothe movable node in a direction perpendicular to the motion of the slidethereby rotating the jaws around the fixed node resulting in the jawsopening and closing; a set of registration dowels attached to the bottomof the housing near the distal end of each of the jaws which arepositioned to be capable of being abutted by the cassette-shaped articleonce the cassette-shaped article has been acquired, a compliance blockis located at the upper end of the housing; and a spring is placed underthe compliance block, enabling the housing to slightly tilt, whereinacquisition of the cassette is guided by the registration dowels and themovement of the cassette-shaped article is guided by the complianceblock and spring allowing for possible misalignment of the apparatusrelative to the cassette-shaped article.
 7. An apparatus for gripping adiagnostic cassette comprising: a housing, a servo motor, a rotatablelead screw driven by said motor, a rack nut, a sector gear linkage, anda set of jaws, wherein the application of electromotive force to theservo motor causes rotation of the lead screw in a first direction whichimparts linear motion to the rack nut in a first direction resulting inrotational movement of the sector gear linkage in the opposite directionproducing an inward rotation of the set of jaws to a predetermined pointwhich allows the diagnostic cassette to be gripped by the jaws.
 8. Anapparatus as claimed in claim 7, wherein upon gripping the cassette, theset of jaws are retracted upward into the housing.
 9. A method forgripping a cassette-shaped article comprising; providing a supporthousing; providing a linear actuator movable along an x-axis relative tothe support; providing a set of jaws for gripping the cassette-shapedarticle, each jaw having a proximal end and a distal end, the distal endbeing adapted for gripping the cassette-shaped article; providing amovable node located at the proximal end of each jaw for connecting eachjaw to the linear actuator; providing a fixed node relative to thesupport located between the proximal and distal end of each jaw forconnecting each of the jaws to the support, wherein the fixed node isindirectly located on the jaws and is connected to the jaws via linkageand a movable node on the jaws; positioning the housing to be locatedabove the cassette-shaped article to be gripped; moving the linearactuator which provides motion to the movable node in an x- and y-axisthereby rotating the jaws around the fixed node resulting in the jawsclosing and acquiring the cassette-shaped article.
 10. A methodaccording to claim 9, further comprising: a sector gear linkage having atoothed side and a linkage extending away from the toothed side, the endof the linkage opposite the sector gear linkage connected to the movablenode; and a rack on the linear actuator, wherein the sector gear linkageteeth and the rack teeth are engaged and where movement of the rackrotates the sector gear linkage imparting motion to the linkage whichimparts motion to the jaws through the movable node.
 11. A methodaccording to claim 10, further comprising providing a set ofregistration dowels, attached to the bottom of the housing near thedistal end of each of the jaws capable of being abutted by thecassette-shaped article once the cassette-shaped article has beenacquired, providing a compliance block, located at the upper end of thehousing, and a spring, placed under the compliance block, enabling thehousing to slightly tilt, wherein acquisition of the cassette is guidedby the registration dowels and the movement of the cassette-shapedarticle is guided by the compliance block and spring allowing forpossible misalignment of the apparatus relative to the cassette-shapedarticle
 12. A method for gripping a cassette-shaped article comprising:providing a support housing; providing a linear actuator movable alongan x-axis relative to the support; providing a set of jaws for grippingthe cassette-shaped article, each jaw having a proximal end and a distalend, the distal end being adapted for gripping the cassette-shapedarticle; providing a movable node located at the proximal end of eachjaw for connecting each jaw to the linear actuator; providing a fixednode relative to the support located between the proximal and distal endof each jaw for connecting each of the jaws to the support, wherein thefixed node is directly located on the jaws; providing a drive linkageconnected to the linear actuator at the center thereof, the drivelinkage having elongated slots on either side of the center, the movablenodes being slidably engaged in the slots, providing a set ofregistration dowels attached to the bottom of the housing near thedistal end of each of the jaws which are positioned to be capable ofbeing abutted by the cassette-shaped article once the cassette-shapedarticle has been acquired, providing a compliance block at the upper endof the housing, and a spring under the compliance block, enabling thehousing to deflect, positioning the housing to be located above thecassette-shaped article to be gripped; moving the linear actuator whichmoves the drive linkage which imparts linear motion to the movable nodein a direction perpendicular to the motion of the slide thereby rotatingthe jaws around the fixed node resulting in the jaws closing andacquiring the cassette-shaped article; wherein acquisition of thecassette is guided by the registration dowels and the movement of thecassette-shaped article is guided by the compliance block and springallowing for possible misalignment of the apparatus relative to thecassette-shaped article.